The present invention relates generally to fire protection sprinkler systems, and more particularly, to a cover plate for a concealed fire sprinkler head.
Sprinkler heads have long been used in automatic fire extinguishing systems in order to controllably disperse a fluid in order to suppress or extinguish a fire in a designated area. Typically, the fluid utilized in automatic fire extinguishing systems is water, however, systems have also been advanced to disperse other fire extinguishing fluids. In one common design, sprinkler heads include a solid metal base with a central orifice having an inlet connected to a pressurized supply of water or other fire extinguishing fluid. A deflector, spaced from the sprinkler body, alters the trajectory of the water in an optimum pattern when discharged from the central orifice. In many conventional sprinkler heads, the deflector is fixedly spaced from the outlet by a pair of rigid arms and mounted on a boss joining the arms. A thermally sensitive trigger assembly is positioned between the deflector, boss and the central orifice outlet and sealingly engages a sealing assembly, which under non-activated conditions, prohibits water flow from the outlet. When the temperature reaches a preselected value indicative of a fire, the trigger assembly releases the sealing member and permits the expulsion of water from the outlet.
In another common design, often referred to in the industry as a concealed, recessed or flush sprinkler head, the structure in which the sprinkler body is positioned has a recess or cavity, sized to enable the insertion of the sprinkler body. The deflector is movably supported proximate to the outlet, with in a cavity formed in the sprinkler body. A housing is attached to, and extends beyond the bottom region of the sprinkler body and includes an annular flange positioned about the exterior perimeter of the cavity in which the sprinkler body is located. A sealing assembly, located within the interior of the sprinkler body, seals the outlet of the sprinkler body and is maintained in a closed position by a pair of pins or actuators depending from the bottom of the sprinkler body. The pins are held in an inwardly biased or closed position by a thermally sensitive trigger assembly, positioned between the sprinkler body and the bottom of the housing, which is thermally responsive in the temperature range indicative of a fire. Under normal temperatures, the presence of the thermally sensitive trigger assembly prohibits fluid flow through the central orifice. When the temperature within the designated area rises to a preselected value due to the presence of fire, the thermally sensitive trigger assembly fuses, or ruptures, causing the pins to move in an outward direction, and in consequence, results in the movement of the deflector away from the outlet of the sprinkler body, with its movement halted a preselected distance within the interior of the designated area. Activation of the thermally sensitive trigger assembly also releases the sealing assembly, enabling pressurized fluid to travel through the sprinkler body and be expelled therefrom. Once expelled from the outlet, the fluid impacts the deflector, and its trajectory is altered in an optimum pattern.
Concealed sprinkler heads are commonly equipped with a concealing cover plate which is coupled to the housing. When the deflector is expelled from the housing, it dislodges the cover plate, causing its motion away from the sprinkler head. Under normal conditions, the cover plate conceals the interior of the sprinkler body from view, and in most instances, completely encloses the bottom of the housing.
As the thermally sensitive trigger assembly in a concealed sprinkler is normally positioned above the annular flange, or, at least co-planar therewith, the presence of a cover plate reduces the air flow received by the thermally sensitive trigger assembly. As the air flow rate impacting the thermally sensitive trigger assembly is reduced, the heat transfer rate to the thermally sensitive trigger assembly also decreases. In consequence of the reduced air flow rate, the thermally sensitive trigger assembly is elevated to the preselected activation temperature at a slower rate, and reduces the response time of the sprinkler head.
In response to slow activation times, cover plates have been provided with a plurality of central openings or slots, often formed in surfaces projecting from the center of the cover plate, to permit the heat to pass therethrough and impact the thermally sensitive trigger assembly. These airway openings, however, draw attention to the cover plate and diminish the cover plate""s ability to perform its function of providing an aesthetic cover that does not visually detract from the ceiling or sidewall in which the sprinkler head is positioned.
Consequently, there is a need for a cover plate which conceals the sprinkler head interior, provides an aesthetic, low profile cover, permits heat to be directed to the thermally responsive trigger assembly, and is configured to be immediately and effectively dislodged from the housing in response to a fire.
According to one aspect of the invention, a concealed sprinkler head includes a thermally sensitive trigger assembly, a housing having a mounting surface and a central opening in fluid communication with the thermally sensitive trigger assembly, and a cover plate including a body member mounted to the mounting surface and having a periphery. The periphery has at least one passageway section and an adjacent periphery section adjacent the passageway section, with the passageway section disposed further from the mounting surface then the adjacent periphery section. A cover plate configured with at least one passageway section formed along the periphery provides an effective structure for enabling the passage of air towards the sprinkler head and thus decreases sprinkler response time while maintaining an aesthetically appealing, low profile appearance.
According to another aspect of the invention, a concealed sprinkler head includes a thermally sensitive trigger assembly, a housing with an annular flange and a central opening in which the thermally sensitive trigger assembly is positioned, and a cover plate having a body member formed with a periphery and a center. At least one mounting tab extends from the periphery, towards the center, and is attached to the annular flange by a fusible material. At least a section of the periphery is configured to permit the passage of air into the central opening and towards the thermally sensitive trigger assembly. Configuring the peripheral region of a cover plate to permit heated air to flow towards the sprinkler head results in greater sensitivity to the sprinkler head, while the at least one mounting tab provides a facile, reliable attachment structure.
According to yet another aspect of the invention, the cover plate includes a body member having at least one undulation formed therein. The undulation forms a passageway section at the periphery of the body member and provides an aesthetically appealing design, while enabling heated air to reach the thermally sensitive trigger assembly, and in consequence, increase the response time thereof.
According to still yet another aspect of the invention, a concealed sprinkler head comprises a sprinkler body having a central orifice with an inlet, an outlet, a deflector movably mounted to the sprinkler body, and a thermally sensitive trigger assembly configured to urge a sealing assembly into sealing engagement with the outlet. A housing is attached to the sprinkler body and has a bottom extending beyond the outlet, while the thermally sensitive trigger assembly is positioned between the outlet and the bottom of the housing. A cover plate is removably mounted to the bottom of the housing, with at least a section of its periphery formed with at least one passageway section configured to enable air to travel between the passageway section and the housing bottom and towards the thermally sensitive trigger assembly.
According to a further aspect of the invention, a concealed sprinkler head comprises a sprinkler body with a central orifice, a deflector movably mounted to the sprinkler body, a sealing assembly for sealing the outlet, and a thermally sensitive trigger assembly configured to releasably urge the sealing assembly into engagement with the outlet of the central orifice. A housing is attached to the sprinkler body and has a central opening and a bottom extending beyond the outlet. The bottom is formed with an annular flange having at least one contact section depending below the annular flange. A cover plate includes at least one mounting section having a contact member. The contact member enables the cover plate to be attached to the annular flange such that in the assembled position, the at least one contact section is in substantial registry with the contact member. The cover plate has a periphery formed with at least one passageway section configured to enable air to travel between the passageway section and the bottom of the housing and towards the thermally sensitive trigger assembly. The registry of the contact member with the contact section depending from of the annular flange provides secure attachment of the annular flange to the cover plate, while the cover plate enables heated air to travel therethrough and contact the thermally sensitive trigger assembly, thereby decreasing response time.
These and other objects, advantages, purposes and features of the invention will become apparent upon review of the following specification in conjunction with the drawings.